For sexual harassment to be unlawful, it must be unwelcome and offensive to the recipient. If an employee asks a co-worker to tell an off-color joke, for example, telling the joke is not harassment.

If a co-worker's request for a date is enthusiastically accepted, the invitation is probably not harassment.

But it's not always easy to tell if the conduct is unwelcome or offensive.

Consider this example: When nude photos of a female employee at a manufacturing plant appeared in nationally-circulated motorcycle magazines, a coworker brought the magazines to work and passed them around. Other co-workers engaged in lewd gossip about her or called her vulgar names. Another circulated a petition to get her fired because of the photographs.

Could a woman who willingly posed nude for a magazine really consider this conduct unwelcome or offensive? In this case, the court thought so.

Despite her questionable out-of-work activities, there was no evidence that she had solicited the attention at work. She did not bring the magazine into the plant. She did not pose in provocative ways at work. She did not tell sexual stories or make sexual gestures or request sexual encounters at work.

In fact, she complained about the offensive comments and quit her job when she couldn't take it anymore. Her conduct outside of work had nothing to do with whether she was offended by comments at work.

Readers who disagree with the conclusions of this court should consider a more cut-and-dry example: A married woman who spurns sexual advances from a stranger at work, but welcomes them from her husband at home. Just because you enjoy something outside of work does not mean that you welcome it at work.

In another case, a female employee at a machine shop occasionally used sexually explicit terms and profanity, laughed briefly at a sex toy a coworker showed her and displayed a postcard depicting male buttocks that her mentor had given her.

Male coworkers had calendars depicting scantily clad or naked women, kept copies of Playboy and Hustler at the plant, passed around sexually-oriented cartoons and used sexually-abusive language to refer to female coworkers. Her mentor also sent her several suggestive postcards in addition to the one she posted.

She complained but the conduct continued. After she quit, she was summoned to the plant to pick up a box of personal items. The box included crude and sexually explicit jokes and cartoons that had been displayed at the workplace but did not belong to her.

Can a woman who occasionally uses profanity, displays a suggestive postcard at her worksite and laughs briefly at a sex toy consider similar conduct by male coworkers to be unwelcome and offensive?

The jury found that she could. Just because someone participates in offensive conduct does not necessarily mean that the conduct is welcome. It's all in the context.

In this case the evidence showed that the woman did not use profanity before or after her work in the plant. She did not bring suggestive materials in to the plant. Her conduct at the plant was an adaptation to a hostile environment, an attempt to fit in. Additional evidence that the conduct was unwelcome included the fact that she complained about the conduct frequently and often left the workplace in tears.

Many courts have observed that in some situations a woman's participation in sexually-charged conduct could be profoundly different than when a man does the same thing. One woman may engage in such conduct defensively. Another woman may make sexually-oriented comments in a playful manner rather than in an intimidating manner.

One lesson of these cases: Don't assume that off-color comments or conduct are acceptable just because a coworker appears to enjoy it. The safest course is to avoid such conduct in the workplace at all times.

Contributing: Jane Howard-Martin is a graduate of Harvard Law School and has practiced employment law for 15 years. E-mail her at JaneHowardMartin@aol.com. Copyright 2002. Jane Howard-Martin. This article should not be construed as legal advice or a legal opinion on any specific facts or circumstances. State employment laws vary; make sure to check what those laws are.